CFD Modeling and Simulation of Hydrodynamics in a Fluidized Bed Dryer with Experimental Validation

Abstract

Gas-solid fluidized bed dryers are used in a wide range of industrial applications. With applying computational fluid dynamic (CFD) techniques, hydrodynamics of a two-dimensional nonreactive gas-solid fluidized bed dryer was investigated. A multifluid Eulerian model incorporating the kinetic theory for solid particles was applied to simulate the unsteady state behavior of this dryer and momentum exchange coefficients were calculated by using the Syamlal-O'Brien drag functions. A suitable numerical method that employed finite volume method was used to discretize the equations. Simulation results also indicated that small bubbles were produced at the bottom of the bed. These bubbles collided with each other as they moved upwards forming larger bubbles. Also, solid particles diameter and superficial gas velocity effect on hydrodynamics were studied. Simulation results were compared with the experimental data in order to validate the CFD model. Pressure drops and bed expansion ratio as well as the qualitative gas-solid flow patterns predicted by the simulations were in good agreement with experimental measurements at superficial gas velocities higher than the minimum fluidization velocity. Furthermore, this comparison showed that the model can predict hydrodynamic behavior of gas solid fluidized bed reasonably well.

Numerical simulation and experimental validation of the hydrodynamics in a 350 kW bubbling fluidized bed combustor

“…Syamlal and O'Brien drag function gives a better results compared to other drag models, and it is more suitable for predicting the hydrodynamics of gas-solid flow in fluidized beds [9,11].…”

“…Hamzehei [9] compared the CFD simulation predicted results using the Syamlal and O'Brien drag model to the experimentally measured pressure drop, and found that the model predictions were in good agreement with the experimental data.…”

“…This drag law is based on the measurements of the terminal velocities of particles in fluidized or settling beds, with correlations which are functions of the volume fraction and the relative Reynolds number [9,15].…”

Simulation study on the effect of air distribution on the bed height and bubble formation in bubbling fluidization reactor

“…A number of researches have been done in order to understand and to determine the best parameters for different fluidized bed application. Mahdi Hamzehei [3] in his study has investigated solid particles diameter and superficial velocity effect on the reactor hydrodynamics using Eulerian-Eulerian model with Syamlal-O'Brian drag function. The pressure drop and bed expansion ratio of the simulation were in good agreement with the experimental data.…”

Numerical Model and Experimental Validation of the Hydrodynamics in an Industrial-Scale Sewage Sludge Bubbling Fluidized Bed Incinerator

“…The three popular and most widely used drag models are Gidaspow, Wen-Yu and Syamlal and O'Brien model [16,[20][21][22]. Syamlal and O'Brien drag model is found to predict better hydrodynamic results compared to other models, and therefore more suitable for investigating the hydrodynamics of gas-solid bubbling fluidized bed combustors [10,16].…”